The goal of this trial is to determine whether or not estrogen replacement therapy shows promise in improving the cognitive, affective and/or physiological function of postmenopausal, hysterectomized females with Alzheimer's disease (AD). Previous reports have suggested that postmenopausal women experience benefits including but not limited to improvement in mood, concentration and memory from estrogen replacement therapy. It has also been suggested that a subset of demented women on estrogen replacemenet therapy experience benefit in the form of improvements in selected areas of cognitive performance. This study is a double-blind placebo-controlled pilot study of two doses of estrogen versus placebo in hysterectomized women over the age of 60. Forty subjects will be enrolled in each cell. The study is 15 months in length with 12 months of exposure to drug/placebo followed by a 3 month single-blind wash-out period. Outcome measures include: global measures, measurement of memory, affect, motor performance, attention, language, functional ability, and quality of life.